After I posted, I went back and reread your original post, and one of your objectives was low coma. I love my Contax 28mm, but I have to say that it does show significant coma when the conditions are right. I have never seen coma in my 50/1.7.
EDIT:
Out of curiosity, I took my 50/1.7 out to check for coma, and it has it. I must have just never used it in conditions where it made it apparent.


